XSR Summary The mission of the Sidney Kimmel Cancer Center X-Ray Crystallography and Macromolecular Characterization Shared Resource (XSR) is to facilitate the design, acquisition, and interpretation of quantitative data relevant to the structure and function of cancer-related macromolecules; decipher the impact of mutations on protein folding and stability; and promote the understanding of macromolecular interactions at atomic detail. The XSR provides a single portal for SKCC members who require crystallization, X-ray data collection, structure determination, and functional dissection of macromolecular interactions. Founded in 2009, the XSR is the only facility of its kind in Philadelphia and is uniquely positioned to fill the needs of cancer biologists in macromolecular structure analysis and characterization by providing a unique array of specialized instruments that build upon expertise in biophysics, structural, and chemical biology. When former XSR Director Dr. John Pascal relocated to the University of Montreal in 2015, Gino Cingolani, PhD, took over as Director of the XSR. Co-Director Michael Root, PhD, continues to oversee the instrumentation dedicated to macromolecular characterization. Anshul Bhardwaj, PhD, the XSR facility manager, oversees the day-to-day operations of the XSR and supports the research of SKCC members through facility services and scientific collaboration. Current XSR goals are as follows: 1) Serve the needs of SKCC research programs in crystallization, X-ray data collection, structure determination, and biophysical characterization of macromolecules; 2) Assist with the design, acquisition, and interpretation of quantitative data relevant to the structure and function of cancer- related macromolecules; 3) Facilitate studies on how mutations impact folding, stability, and interactions of proteins important in oncogenesis.